Question

Which of the following best describes this process?

(a) ATP is being hydrolyzed to phosphorylate the substrate.
(b) The energy derived from substrate oxidation is coupled to the conversion of ADP to ATP.
(c) Two successive phosphates are transferred, first to AMP, then to ADP, finally forming ATP.
(d) The substrate is hydrolyzed using ATP as an energy source.

Answer 1

The best description for the process of generating ATP by directly using the energy derived from the oxidation of a substrate to convert ADP to ATP is substrate-level phosphorylation, which corresponds to option (b).

Step-by-step explanation:

The process that best describes the given information is substrate-level phosphorylation, where a phosphate group is removed from an intermediate reactant during the catabolism of glucose, and the free energy released from that reaction is utilized to add the third phosphate to an ADP molecule, thus generating ATP. The correct option that describes this process is (b) The energy derived from substrate oxidation is coupled to the conversion of ADP to ATP. This is because during substrate-level phosphorylation, energy from the substrate, which is in an oxidized state, is used directly to convert ADP into ATP without the involvement of any electron transport chain or chemiosmosis.

An example of this occurrence is during glycolysis, specifically, the reaction catalyzed by the enzyme phosphoglycerate kinase, where 1,3-bisphosphoglycerate donates its high-energy phosphate to ADP, forming ATP and 3-phosphoglycerate. This type of phosphorylation is distinct as it does not require the presence of a proton gradient, unlike oxidative phosphorylation.